The GTC exoplanet transit spectroscopy survey II: An overly-large Rayleigh-like feature for exoplanet TrES-3b
The GTC exoplanet transit spectroscopy survey II: An overly-large Rayleigh-like feature for exoplanet TrES-3b
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DOI：
10.1051/0004-6361/201526313
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发表时间：
2015-10
期刊：
影响因子：
--
通讯作者：
H. Parviainen;E. Pall'e;L. Nortmann;G. Nowak;N. Iro;F. Murgas;S. Aigrain
中科院分区：
文献类型：
--
作者：
H. Parviainen;E. Pall'e;L. Nortmann;G. Nowak;N. Iro;F. Murgas;S. Aigrain
我们开始使用 OSIRIS@GTC 观测到的覆盖 530 至 950 nm 波长范围的地面透射光谱来搜索 TrES-3b 大气中的瑞利散射以及 K 和 Na 吸收特征。我们的分析基于贝叶斯方法，其中覆盖一组给定通带的光变曲线与 PHOENIX 计算的恒星边缘变暗轮廓联合拟合。该分析是在假设白色和红色（时间相关）噪声的情况下进行的，并使用两种方法（高斯过程和除以白色）来解释红色噪声。初步分析揭示了透射光谱，显示出朝向光谱蓝色端的消光有强烈的瑞利样增加，并且在 767 nm 附近的 K I 共振双峰周围消光增强。然而，信号幅度明显大于理论考虑的预期。详细分析表明，类 K I 特征完全是由于大地 O$_2$ 吸收的变化造成的，但类瑞利特征仍然无法解释。
We set to search for Rayleigh scattering and K and Na absorption signatures from the atmosphere of TrES-3b using ground-based transmission spectroscopy covering the wavelength range from 530 to 950 nm as observed with OSIRIS@GTC. Our analysis is based on a Bayesian approach where the light curves covering a set of given passbands are fitted jointly with PHOENIX-calculated stellar limb darkening profiles. The analysis is carried out assuming both white and red -- temporally correlated -- noise, with two approaches (Gaussian processes and divide-by-white) to account for the red noise. An initial analysis reveals a transmission spectrum that shows a strong Rayleigh-like increase in extinction towards the blue end of the spectrum, and enhanced extinction around the K I resonance doublet near 767 nm. However, the signal amplitudes are significantly larger than expected from theoretical considerations. A detailed analysis reveals that the K I-like feature is entirely due to variability in the telluric O$_2$ absorption, but the Rayleigh-like feature remains unexplained.